Fix Bug in testSplitWithPrimaryActivity

[1] changed the reference implementation to
launch the secondary activity in the existing
secondary container if the split presentation
matches, so this CL updates the test accordingly.

[1] Iad6d238c6dfb009402376a725136be6c6fdab98c

Bug: b/222188067
Test: atest ActivityEmbeddingLaunchTests#testSplitWithPrimaryActivity
Change-Id: I21324569e42b6c2d81a991a5076a517f7f8281e5
1 file changed